TUCSON, Ariz. - Jared Loughner had never been in major trouble with the law or overtly violent, but his behavior at his community college was so disturbing that campus police gave him and his parents an ultimatum: Get a mental health evaluation or don't come back.

Loughner went away but his deteriorating mental condition didn't. Just more than three months later, he is charged in a horrific mass shooting that killed six people and left Rep. Gabrielle Giffords gravely wounded with an uncertain recovery.

For those living with mentally ill family members or friends, the tragedy plays on their deepest fears and raises a more heart-wrenching and personal question: When and how should loved ones intercede to force someone to get help?

Parents who suspect their child might have a major mental illness face an array of emotional and bureaucratic hurdles, from their own fears to strict laws that limit involuntary commitment to severe cuts in services. For many, the battle for intervention and treatment is a never-ending nightmare.

"I would bet that every parent who has a son or daughter with schizophrenia or bipolar disorder or any major brain disorder all feel the same thing now: There but for the grace of God go I," said the mother of a 35-year-old son with schizophrenia, who has been off his medication for nine years. The woman requested anonymity because she believes her son - an avid reader of Internet news - would sever contact with her forever for speaking to the media.

"My heart goes out to the family," the mother said. "They didn't cause this, you can't cause a brain disorder in your family."

Police are also hamstrung by legitimate concerns about civil rights and due process that are rooted in historic abuses of the mentally ill, said Timothy Schmaltz, chief executive of the Phoenix-based group Protecting Arizona's Family Coalition.

In Loughner's case, it appears that despite the concerns of campus police, professors and other classmates, the 22-year-old was never diagnosed with what experts say seems to be a clear-cut case of schizophrenia.

That he fell through the ever-widening cracks of the mental health system is an all-too-common scenario for families who might want help with a major mental illness. They are confronted with an overwhelming struggle - a fight that often begins with the person they're trying to help.

One of the key symptoms of schizophrenia, for example, is a lack of awareness and denial that anything is wrong, said Mark A. Kalish, a practicing psychiatrist who also teaches at the University of California, San Diego.

This means that even as a person's behavior spins increasingly out of control, they refuse treatment. In many states, adult patients cannot be involuntarily committed unless they are found by a court to be a danger to themselves or others.

The mother with the schizophrenic child said her son experienced his first symptoms at college at age 20. He endured two hospitalizations - one voluntary and one involuntary - but then stopped taking his medicines, skipped his medical appointments and eventually moved away from his home state.

His parents are powerless to intervene. They send him money each month, but long ago gave up pressuring him to take his medication in order to have any contact at all, his mother said.

"Your hands are tied. If it happened when they were 16, you could take them to a hospital and admit them and they have nothing to say about it," she said. "But once they're legally an adult it's just a horrible thing to go through for the family.

"He doesn't believe he has a mental illness at all. He's psychotic," she said. "The longer you try to get someone help, the more they shut you out and don't share what's going on."

She said she sought and received help from the National Alliance on Mental Illness, a national, grassroots advocacy organization, when her son was first diagnosed.

It's unclear what the Loughners did, if anything, to get their son help after the meeting with campus police and it's also unclear if the college reported his bizarre behavior to local authorities. College officials did not return calls.

In the wake of the Virginia Tech killings on April 16, 2007, the federal government set up teams from the Department of Education and the FBI to determine how to identify individuals whose behavior causes concern or is disruptive and assess whether the person has the intent or ability to carry out an attack. The Virginia Tech shooter, Seung-Hui Cho, had been involuntarily committed to outpatient therapy by a judge before killing 32 people and himself.

Arizona has one of the most flexible statutes for involuntary commitment and allows anyone with knowledge of the person's behavior - a teacher, a parent, a police officer, a friend - to petition for a court-ordered mental health evaluation, the first step toward involuntary treatment, said Kristina Ragosta, legislative and policy counsel at the Treatment Advocacy Center in Arlington, Va.